Docs: Fix anchor in 'docs/developer-guide/working-with-rules.md' (#14332)
Docs: Fix anchor in 'docs/developer-guide/working-with-rules.md' (#14332)

Fixes the `getSourceCode()` anchor ref.
platinumazure/eslint,eslint/eslint,Trott/eslint,DavidAnson/eslint,Trott/eslint,platinumazure/eslint,DavidAnson/eslint,eslint/eslint